Foaming problems can occur during the high temperature processing of hydrocarbon fluids. Crude oil towers and cokers operating at high temperatures can produce foam in their hydrocarbon products which in turn diminishes the efficiency of the tower or coker, degrading the quality of the overhead products such as gasoline and gas oils. Severe foaming problems are often encountered in crude oils during separation of dissolved gases at the well head.
In the processing of various residual petroleum stocks into coke, a commonly used technique is the well known delayed coking process. In the delayed coking process, heavy residual oils are heated to about 500.degree. C. by pumping them at high velocity through a pipe furnace and then charging these oils to an insulated coking drum. The delayed coking process produces a quantity of foam which is undesirable since it diminishes the efficient operation of the process.
Other refinery processes that can experience foaming problems include crude oil distillation, vis breaking, and solvent or super critical fluid deasphalting units. Traditionally, silicone (dimethyl polysiloxane) defoamer compounds were employed to treat these operations for foaming problems.
The use of silicone defoamer compounds is economically attractive due to the need of low dosage levels in the hydrocarbons. However, they are expensive with respect to using them in less expensive, lower quality hydrocarbon fluids. Silicone defoamer compounds also pose a problem due to their difficulty in dispersing in high temperature hydrocarbon systems. The silicone compounds also tend to react with the metal surfaces of the processing system. In particular, they poison the catalyst used for hydrotreating crude oil fractions.
Similarly, problems occur when non-silicone defoamer compounds are employed as they can only knock down the foam head in a delayed coker unit to a certain extent and do not completely collapse the foam head.